I am beginning a new project and I am at the step where I need to sketch my Layouts. Thing is sketching with a pencil on paper is not very appealing . Suddenly I thought about doing those sketches on an iPad .
So I wonder if some of you are already going that way, and if so which app they use. I consider that it should be able to draw vectors, in this way you can erase easily, and that it should support layers.
Exporting to an image format like JPG would be very nice to include in documentation !